NEW YORK — With the 55th and last swing on the longest of many long points in the U.S. Open final, Rafael Nadal pushed a backhand into the net to get broken by Novak Djokovic.

It could have been the beginning of the end for many players.

Not for Nadal, who is as resilient as they come. A year after watching the Flushing Meadows title match on TV at home with a bad left knee, he is fit as can be – and, just maybe, better than ever.

The No. 2-ranked Nadal emerged with his 13th Grand Slam title, and second at the U.S. Open, by withstanding No. 1 Djokovic's similar brand of hustle-to-every-ball style and pulling away Monday to a tense, taut 6-2, 3-6, 6-4, 6-1 victory.

"This season is probably the most emotional one in my career. I felt that I did everything right to have my chance here," said Nadal, who dropped to the court and rolled over on his stomach, crying, after the last point. "I have to be almost perfect to win."

Hard to believe this is the same Nadal who missed seven months with a knee injury, but was able to cover every inch of the court, tracking down shot after shot from Djokovic.

Hard to believe this is the guy who used to be considered a clay-court specialist, but is 22-0 on hard courts in 2013.

"I never thought something like this could happen," Nadal said. "I feel very lucky about what happened since I came (back). It's true that I worked, but even like this you need luck to be where I am today."

He and Djokovic started in sunlight and finished at night, a 3-hour, 21-minute miniseries of cliffhangers and plot twists with a pair of protagonists who inspired standing ovations in the middle of games.

There was no quit in either of them, during points that lasted 15, 25, even more than 50 strokes. Those rallies went so long, rarely over when they appeared to be, and spectators often shouted out during the course of play, prompting Nadal to complain to the chair umpire.

"It's what we do when we play against each other, always pushing each other to the limit," Djokovic said. "That's the beauty of our matches and our rivalry, I guess, in the end."

This was their 37th match against each other, the most between any two men in the Open era, and Nadal has won 22. It also was their third head-to-head U.S. Open final in the last four years. Nadal beat Djokovic for the 2010 title, and Djokovic won their rematch in 2011.

They know each other's games so well, but in the end, it was Nadal who was superior.

"He was too good. He definitely deserved to win this match today and this trophy," Djokovic said. "Obviously disappointing to lose a match like this."

Djokovic, who won the Australian Open in January, will hold onto his No. 1 ranking for the time being. But it's clear to everyone who the top player in tennis is at the moment.

Nadal is 60-3 in 2013 with 10 titles, including at the French Open, which made him the first man with at least one Grand Slam trophy in nine consecutive seasons. The 27-year-old Spaniard's total of 13 major championships ranks third in the history of men's tennis, behind only Roger Federer's 17 and Pete Sampras' 14.

Nadal has won a record eight titles at the French Open, two each at the U.S. Open and Wimbledon, and one at the Australian Open.

"Thirteen Grand Slams for a guy who is 27 years old is incredible," said Djokovic, who owns six himself. "Whatever he achieved so far in his career, everybody should respect, no question about it."

Nadal no longer wears the strips of white tape he once used to bolster his left knee, and the way he covered the court against Djokovic – switching from defense to offense in a blink – proved that while he says he still feels pain in that leg, he definitely does not have problems moving around.

"The hardest part is the pain, always," Toni Nadal, Rafael's uncle and coach, told The Associated Press. "You have pain, and you play. But the problem is you never know if you can run so fast, like before, or if you can play against the best players. From one day to (the next), it's difficult, always."

Nadal sure has managed to hide it well. He improved to 8-3 against Djokovic in Grand Slam matches, including a thriller of a semifinal at the French Open, which Nadal won 9-7 in the fifth set after trailing.

These two also played the longest Grand Slam final in history, a nearly six-hour struggle that left both needing to sit in chairs during the ceremony after Djokovic's victory at the 2012 Australian Open.

This time, Nadal was relentless from shot to shot, yes, and from point to point, too, but what might have been most impressive was the way he stayed steady when Djokovic recovered from a rough start and began asserting himself.

At the outset, Djokovic was his own worst enemy on many points, a touch or two off the mark. Nadal claimed 12 of the last 14 points in the first set, with Djokovic looking almost bored.

The world saw this sort of listless, lackluster Djokovic two months ago in the final at Wimbledon, where Nadal had exited a Grand Slam tournament in the opening round for the only time in his career. That time, Djokovic went through a difficult semifinal – at 4:43, the longest in Wimbledon history – and barely put up much resistance in a straight-set loss to Andy Murray two days later.

In New York, Djokovic was coming off another four-hour semifinal victory, and the key stat in the first set Monday was that he made 14 unforced errors, 10 more than Nadal.

There were no surprising or innovative tactics from Nadal. In the simplest of terms, he reached nearly every ball Djokovic delivered, and Nadal's replies nearly never missed the intended spot, accented by his huge uppercut of a swing and loud grunts of "Aaaah!" By match's end, Djokovic had made 53 unforced errors, Nadal only 20.

"Credit to my opponent. He was making me run," Djokovic said. "I had my ups and downs."

The Serb's biggest ups came in the second set. Nadal was broken a grand total of once through his first six matches in the tournament – a string that reached 88 games by early in the final's second set. But with Djokovic raising his level, and gaining control of more of the many extended exchanges, he broke Nadal three times in a row.

"Novak was playing just amazing," Nadal said. "When Novak plays (at) that level, I am not sure if (anybody) can stop him."

The initial break came for a 4-2 lead in the second set, thanks to the crescendo of that 55-swing exchange. Djokovic used superb defense to elongate the point, tossing his body around to bail himself out repeatedly by blunting Nadal's violent strokes. When the memorable point ended, Djokovic bellowed and raised both arms, and thousands of fans rose to their feet, chanting his nickname, "No-le! No-le!"

Now Djokovic was energized, and Nadal was suddenly in a tad of trouble.

As Toni Nadal put it: "Rafael was always there, there, there. ... He was so strong in his mind. That was the difference."

The final momentum shift came with Nadal serving at 4-all in the third set. Djokovic earned three break points, thanks in part to a tremendous lob-volley and another point when Nadal slipped and tumbled to his backside.

But a quick forehand winner by Nadal, a forehand into the net by Djokovic on a 22-stroke point, and a 125 mph ace – Nadal's only one of the evening, it drew shouts of "Vamos!" from Uncle Toni – helped avoid another break.

"I didn't do anything I felt (was) wrong in these few points," Djokovic said. "He didn't make a mistake."

In the very next game, Nadal broke Djokovic's serve and, apparently, his will. When that set ended with Djokovic pushing a forehand long on a 19-shot point, Nadal screamed as he knelt down at the baseline, his racket on the court and his left fist pumping over and over and over.

"A really important set," Nadal called it later, "and a really special one."

Djokovic made one last serious stand, holding break points in the fourth set's first game, but Nadal saved those, then immediately broke to go ahead 2-0.

Once again, Nadal withstood Djokovic's best and was on his way to another Grand Slam celebration.

Afterward, his newest silver trophy at arm's reach, Nadal was asked about catching the only two men who've won more.